DIY Doctor UK DIY Forums

Hi, I’m looking for some much needed advice about a single story side extension that I had built 4 years ago.
The original builder dug the foundations out and found a pipe. He told me that this was an old rainwater or soakaway drain that was no longer in use so wouldn’t be a problem. It is not part of my sewage drains as they are on the other side of the garden. So I had no reason to doubt him at the time. Anyway the next day the foundations had filled up with water and it had no rained. When questioned he said that the drain must have emptied out but was now empty. This happened for the next couple of days and he had to hire a pump to get the water out. I was very worried but he said that once the concrete was poured it was seal the drain up. The building inspector never questioned the foundations so I thought everything was ok.
The building inspector did ask for a block and beam floor to be laid. Once the concrete was poured I noticed that the water filled up in the middle where they had dug down for the block and beam floor. The water was still filling up the hole but it had been raining heavily so that was the reason I was told it had happened.
The walls went up and the floor down and as days turned into weeks and weeks into months we were messed about by the builder. He turned up late, didn’t turn up at all, we had countless arguments and he finally walked and didn’t come back and I had a shell with no roof and no windows. We had stupidly paid him and as he kept asking for more money and we said no, he said ok and left us right in it.
We had to get another builder to finish the job which cost a fortune and the building inspector made us rip stuff out and start again as it was all wrong. By this time we were well fed up, had ran out of money and wanted the shell finished.
The first thing I noticed was that the extension was very cold, much colder than the existing house. This made no sense as it was more insulated than the existing house. There is insulation in the walls, floor and roof.
As weeks went by there was a horrible musty smell in the extension (which was meant to be a bedroom for my son) and it was even colder. The skirting boards began to fall off and the laminate floor sunk in the corners. I was very worried by this point and moved my son out of the room. There is green mould on the outside walls where the floor meets the extension the whole way round and the soil is very damp, even when it dry outside.
My main issue is I have no idea who to call and who will tell me what is wrong. I trust no one and cannot afford to be ripped off again. I have saved some money to try and get the problem fixed but it cannot be wasted.
My fence fell over and the post had to be put back in and when my uncle dug down the hole was full of water and this particular fence post is in line with my extension foundations and in line with where this pipe was running.
Can anyone give me some advice about what could be wrong and who I can turn to please?

The amount of water in the ground your describing suggests that a water pipe may be leaking, because you describe that even in dry conditions the ground is still wet. So it needs checking first.
It would also need a soakaway pipe laying, leading away from the property, and a large pit dug in the garden to take the water.
So, a plumber is needed, to check for a leak,and a new main laid if needed.
and an experienced groundworker to lay the soakaway.